Hiroaki Ikegami

New Direct Color Mapping Method for Reducing the Storage Capacity of Look-Up Table Memory

Direct color mapping method using 3-dimensional look-up table is promising for high accuracy and high speed color correction, instead of matrix masking method. But it needs large storage capacity which leads to cost increase. So various ideas using interpolation technique were proposed for reducing the storage capacity. This time, two new ideas for reducing the storage capacity are introduced and evaluated. One is to eliminate the part of 3-dimensional look-up table memory corresponding to the outside of color gamut of output device. Its reduction ratio is about 25%. The other is to reduce the look-up tables instead of multiplier for 3 X 3 matrix interpolation. Its reduction ratio is about 20% in the case of 8 bit X 3 input and 8 bit X 3 output using lower 3 bit interpolation. By the combination of these ideas, the storage capacity can be reduced down to 100k byte in that case.